Pick proof locking plate for padlock

ABSTRACT

A cylinder assembly located in the chamber of a padlock has a key actuated rotating cylinder plug to which is attached a locking plate. Locking lugs at opposite ends of the locking plate engage notches in the long and short legs of a shackle to hold the shackle in locked position. Engagement of the lugs with the notches is such that when the lug engaging the short leg is clear, the lug engaging the long leg is still partly engaged. For that reason the shackle cannot be unlocked by unauthorized manipulation of a shim inserted through the clearance around the short leg of the shackle to release the locking lug from engagement with the short leg.

United States Patent Fane et al.

[ 1 Apr. 4, 1972 [54] PICK PROOF LOCKING PLATE FOR PADLOCK [72]Inventors: William J. Fane, Burnaby, British Columbia, Canada; VernardW. Sanders, Los

21 Appl. No.: 64,514

[56] References Cited UNITED STATES PATENTS 2,433,114 12/1947 Gray..70/38A 3,008,318 11/1961 Gutman ..70/38A 2,842,950 7/1958 Soref..70/38 B 2,703,975 3/ 1955 Ryndzonak ....70/52 X 2,824,439 2/1958 Soref..70/52 X Primary Examiner-George F. Mautz Assistant Examiner-Edward J.McCarthy Attorney-Beehler & Arant [57] ABSTRACT A cylinder assemblylocated in the chamber of a padlock has a key actuated rotating cylinderplug to which is attached a locking plate. Locking lugs at opposite endsof the locking plate engage notches in the long and short legs of ashackle to hold the shackle in locked position. Engagement of the lugswith the notches is such that when the lug engaging the short leg isclear, the lug engaging the long leg is still partly engaged. For thatreason the shackle cannot be unlocked by unauthorized manipulation of ashim inserted through the clearance around the short leg of the shackleto release the locking lug from engagement with the short leg.

7 Claims, 6 Drawing Figures PATENTEDAPR 4 I972 3,653,213 5 w in; .1.

JANE/V7025. y 4y 77/24/014 J IQ/VE 20 FEW/W20 IV. SPA/DEBS PICK PROOFLOCKING PLATE FOR PADLOCK When a padlock is one equipped with a shacklehaving one long leg and one short leg the preferred construction is suchthat there is a reasonably snug fit around the long leg and a ratherloose fit around the short leg. What accounts for this is that the longleg is to be fitted in what amounts to a bearing aperture in which someportion of the long leg remains at all times but there should be arelatively greater clearance in the aperture which accepts the short legso that the short leg can be readily pushed back into the aperturewhenever the shackle is to be snapped shut. When a rotating lockingplate is made use of to engage both shackles whereby to hold the shacklein locked position, if the lock is to be picked, some unauthorized meanssuch as a thin shim, needs to be used to rotate the locking plate out ofits engagement with the legs. Those skilled in the manipulation ofpadlocks are aware that if such a padlock is to be picked, the shim willneed to be manipulated through the relatively large clearance around theshort leg, since the bearing-like clearance around the long leg is notnormally sufficient to permit such manipulation.

It is therefore among the objects of the invention to provide a new andimproved locking means for a padlock which is arranged in such fashionthat it cannot be moved from its normally locked position byunauthorized manipulation.

Another object of the invention is to provide a new and improvedrotating locking means for locking the legs of a padlock shackle whichis arranged in such fashion that the locking means cannot be completelydisengaged by manipulation through the clearance around the short leg.

Still another object of the invention is to provide a new and improveddouble locking means for both legs of a padlock shank which engages thelegs through a rotating movement and wherein the rotating means is soconstructed and assembled that it inherently resists unauthorizedtampering such as might be attempted to rotate the double locking meansout of its locked position.

Still another object of the invention is to provide a new and improvedsimple rotating means capable of engaging both legs of a padlock shackleand which by virtue of its mounting construction is substantially tamperproof.

With these and other objects in view, the invention consists in theconstruction, arrangement, and combination of the various parts of thedevice, whereby the objects contemplated are attained, as hereinafterset forth, pointed out in the appended claims and illustrated in theaccompanying drawings.

In the drawings:

FIG. 1 is a side elevational view of a device partially broken away toshow the locking portion.

FIG. 2 is a cross-sectional view on the line 22 of FIG. 1.

FIG. 3 is a cross-sectional view on the line 3-3 of FIG. 1.

FIG. 4 is a fragmentary cross-sectional view through the short legrevealing the effect of manipulation by anunauthorized shim.

FIG. 5 is a fragmentary cross-sectional view of a long leg showing thecontinued partial engaged position of the locking lug such as mightoccur when the short leg locking lug is being tampered with.

FIG. 6 is a view similar to FIG. 4 revealing another effect ofmanipulation by an unauthorized shim.

In the embodiment of the invention chosen for the purpose ofillustration there is shown a padlock indicated generally by thereference character 10, comprising a case or body 11, made up of amultiple number of laminations 12 held together by rivets 13. In thebody 1 1 is a chamber 14in which is housed a cylinder assemblycomprising a cylinder plug housing 15 and a pin tumbler housing 16. Inthe cylinder plug housing 15 is a rotating cylinder plug 17 to whichaccess is had by way of a key (not shown) and a keyway 17' through anopening in a bottom plate 18. A shackle 19 has a long leg 20 and shortleg 21. To accommodate the long leg 20 there is provided a bearingaperture 22 in a top plate 23 and a second axially aligned bearingaperture 24 in an intermediate lamination 25. The clearance between thebearing apertures 22 and 24 and the outer circumference of the long leg20 is customarily made reasonably close which it can be inasmuch as someportion of the long leg 20 always remains in the apertures 22, 24,removal of the long leg 20 being prevented by engagement of a stop lug26 with the intermediate lamination 25 when the shackle 19 is releasedto the extent of its movement.

At the inner end of the cylinder plug 17 is a projection 27 whichengages a locking plate 28. Parallel surfaces 29 and 30 are positionedto engage respective stops 31 and 32 on the locking plate 28 so thatwhen the cylinder plug 17 is rotated in a counterclockwise direction asviewed in FIG. 2, the locking plate 28 will likewise be rotated in acounterclockwise direction. A certain amount of lost motion is allowedfor when the cylinder plug 17 is rotated in an opposite or clockwisedirection until the parallel surface 29 engages a tab 33 which projectsdownwardly from the intermediate lamination 25.

At one end of the locking plate 28 is a heel locking lug 35 and at theopposite end is a toe locking lug 36. The heel locking lug 35 is adaptedto engage in a heel notch 37 in the long leg 20 and the short leg 21 hasa toe notch 38 which is adapted to be engaged by the toe locking lug 36.The engaged relationship is shown in FIGS. 1 and 2.

A torsion spring 40 which extends around a boss 41 at the outer end ofthe projection 27 of the cylinder plug 17, has one end 42 adapted tobear against the toe locking lug 36 and another end 43 adapted to bearagainst a wall 44 of the chamber 14. Stops 45 and 46 by engagement withthe wall 44 prevent the torsion spring 40 from rotating the locking lugs35, 36 out of engagement with the notches.

To open the lock by normal authorized means a key (not shown) isinserted into a keyway l7, visible in FIG. 2, and the key is rotated ina counterclockwise direction as viewed in FIG. 2 until the locking lugs35 and 36 are disengaged entirely from the respective notches 37 and 38.When this occurs the shackle 19 is released and the locking plate 28remains in rotated position, held there by contact of the round portionof the long leg 20 with an adjacent edge 34 and the heel locking lug 35.

The shackle 19 can be re-engaged by merely pushing the short leg 21 intoaccess apertures 48 and 49, respectively, in the top plate 23 andintermediate lamination 25. As soon as the notches 37 and 38 coincide inposition with the locking lugs 35 and 36, the torsion spring 40 willagain take over and rotate the locking plate 28 clockwise, as viewed inFIG. 2, into an engaging position with the shackle legs 20, 21.

Those experienced in lock construction and who might undertake todisengage the locking plate 28 from engagement with the legs of theshackle l9 understand that clearance between the access apertures 48 and49 and the exterior circumference of the short leg 21 is customarilymade sufficiently wide for ease of re-entry of the short leg 21. A knownexpedient is to inject a relatively thin, stiff shim 50, shown in FIGS.3 and 4, through the clearance and undertake to pry the toe locking lug36 out of its engagement with the toe notch 38 by rotating it.

As shown to good advantage in FIG. 6, the toe locking lug 36 is providedwith a corner cut-out 39 to provide a still further obstacle tounauthorized release of the shackle. The location of the cut-out 39 issuch that when the shim 50 is initially pressed into engagement with thetoe locking lug 36 the shim will be trapped in the cut-out 39. Thedirection of applied pressure is at an angle with respect to thelocation of the toe locking lug such that one component acts along thelongitudinal axis of the locking plate 28 which, since the locking plateis not shiftable axially, additionally discourages the prospect ofdislodging it from locked position by shim action.

Although in the device herein disclosed such a manipulation might bemade possible by moving the shim 50 to the position shown in FIGS. 3 and4, wherein the disengagement of the toe locking lug 36 is complete, thelocking plate 28 is so constructed that the heel locking lug 35 remainsin engagement with the heel notch 37 as shown in FIGS. 3 and 5. Thisremains true even though a substantial part of the heel locking lug 35has been shifted from its position of full engagement. As long as anyportion of the heel locking lug 35 remains in the notch 37, the long leg20 is not released and the padlock remains locked. Clearance between theexterior of the long leg 20 and the bearing apertures 22 and 24 iscustomarily made so snug that it will not admit injection of a secondshim of sufficient size or strength to manipulate the heel locking lug.

Moreover, in spite of the tampering which might be undertaken, no damageis done to the lock and once the shim 50 is removed the lock can beunlocked and relocked in the customary fashion.

While the invention has herein been shown and described in what isconceived to be a practical and effective embodiment, it is recognizedthat departures may be made therefrom within the scope of the invention,which is not to be limited to the details disclosed herein but is to beaccorded the full scope of the claims so as to embrace any and allequivalent devices,

Having described the invention, what is claimed as new in support ofLetters Patent is: I

1. An anti-tamper padlock construction comprising a padlock body havinga chamber therein, a shackle having a long leg and a short leg, saidbody having a bearing aperture on one side in which said long leg isrotatably and slidably secured and an access aperture on the other sidefor reception of the short leg, a cylinder lock assembly mounted in saidchamber and having a cylinder plug extending into the chamber adjacentsaid apertures, a locking plate in operating engagement with saidcylinder plug and adapted to be rotated thereby out of a lockedposition, said long leg having an inwardly facing heel notch and saidshort leg having a toe notch facing said heel notch, said locking platehaving a radially outwardly extending heel locking lug adapted to engagein said heel notch and an opposite radially outwardly extending toelocking lug adapted to engage in said toe notch, the relationship of theheel locking lug, the toe locking lug, the heel notch and the toe notchbeing one wherein when the toe locking lug is clear of the toe notch andadjacent thereto the heel locking lug is in engagement with the heelnotch, whereby unauthorized disengagement separately of said toe lockinglug will fail to release said shackle.

2. An anti-tamper padlock construction as in claim 1 wherein the lockinglugs are diametrically opposite each other and the trailing edge of theheel locking lug is laterally offset relative to trailing edge of thetoe locking lug.

3. An anti-tamper padlock construction as in claim 1 wherein clearancebetween the short leg and the access aperture is greater than clearancebetween the long leg and the bearing aperture.

4. An anti-tamper padlock construction as in claim 1 wherein there is atop end plate forming part of said body and closing said chamber andwherein when the shackle is in locked position the notches in the legsare locked adjacent an inside face of said top end plate.

5. An anti-tamper padlock construction as in claim 1 wherein there is acut-out in a portion of said toe locking lug on the side thereof facingthe short leg access aperture and a side of said cut-out extending intoand out of said access aperture whereby to trap movement of anunauthorized instrument inserted between the short leg and said shortleg access aperture when the shackle is in locked position.

6. An anti-tamper padlock construction comprising a padlock body havinga chamber therein, a shackle having a long leg and a short leg, saidbody having a bearing aperture on one side in which said long leg isrotatably and slidably secured and an access aperture on the other sidefor reception of the short leg, a cylinder lock assembly mounted in saidchamber and having a cylinder plug extending into the chamber adjacentsaid apertures, a locking plate in operating engagement with saidcylinder plug and adapted to be rotated thereby out of a lockedposition, said long leg having an inwardly facing heel notch and saidshort leg having a toe notch facing said heel notch, said locking platehaving a radially outwardly extending heel locking lug adapted to engagein said heel notch and an opposite radia ly outwardly extending toelocking lug adapted to engage in said toe notch, said toe locking lughaving a cut-out at a portion thereof facing the short leg accessaperture with a side extending into said access aperture in lockedposition of said toe locking lug whereby to trap movement of anunauthorized instrument inserted between the short leg and said shortleg access aperture when the shackle is in locked position and guidemovement of said instrument in a direction nonproductive of release ofsaid toe notch.

7. An anti-tamper padlock construction as in claim 6 wherein said sideof the cut-out has a portion at a location greater in radial distancefrom the axis of rotation of said locking plate and outside said accessaperture than is the bottom of the cut-out, said side having a potentialdirection of movement against said unauthorized instrument when saidlocking plate is subjected to unauthorized rotation.

1. An anti-tamper padlock construction comprising a padlock body having a chamber therein, a shackle having a long leg and a short leg, said body having a bearing aperture on one side in which said long leg is rotatably and slidably secured and an access aperture on the other side for reception of the short leg, a cylinder lock assembly mounted in said chamber and having a cylinder plug extending into the chamber adjacent said apertures, a locking plate in operating engagement with said cylinder plug and adapted to be rotated thereby out of a locked position, said long leg having an inwardly facing heel notch and said short leg having a toe notch facing said heel notch, said locking plate having a radially outwardly extending heel locking lug adapted to engage in said heel notch and an opposite radially outwardly extending toe locking lug adapted to engage in said toe notch, the relationship of the heel locking lug, the toe locking lug, the heel notch and the toe notch being one wherein when the toe locking lug is clear of the toe notch and adjacent thereto the heel locking lug is in engagement with the heel notch, whEreby unauthorized disengagement separately of said toe locking lug will fail to release said shackle.
 2. An anti-tamper padlock construction as in claim 1 wherein the locking lugs are diametrically opposite each other and the trailing edge of the heel locking lug is laterally offset relative to trailing edge of the toe locking lug.
 3. An anti-tamper padlock construction as in claim 1 wherein clearance between the short leg and the access aperture is greater than clearance between the long leg and the bearing aperture.
 4. An anti-tamper padlock construction as in claim 1 wherein there is a top end plate forming part of said body and closing said chamber and wherein when the shackle is in locked position the notches in the legs are locked adjacent an inside face of said top end plate.
 5. An anti-tamper padlock construction as in claim 1 wherein there is a cut-out in a portion of said toe locking lug on the side thereof facing the short leg access aperture and a side of said cut-out extending into and out of said access aperture whereby to trap movement of an unauthorized instrument inserted between the short leg and said short leg access aperture when the shackle is in locked position.
 6. An anti-tamper padlock construction comprising a padlock body having a chamber therein, a shackle having a long leg and a short leg, said body having a bearing aperture on one side in which said long leg is rotatably and slidably secured and an access aperture on the other side for reception of the short leg, a cylinder lock assembly mounted in said chamber and having a cylinder plug extending into the chamber adjacent said apertures, a locking plate in operating engagement with said cylinder plug and adapted to be rotated thereby out of a locked position, said long leg having an inwardly facing heel notch and said short leg having a toe notch facing said heel notch, said locking plate having a radially outwardly extending heel locking lug adapted to engage in said heel notch and an opposite radially outwardly extending toe locking lug adapted to engage in said toe notch, said toe locking lug having a cut-out at a portion thereof facing the short leg access aperture with a side extending into said access aperture in locked position of said toe locking lug whereby to trap movement of an unauthorized instrument inserted between the short leg and said short leg access aperture when the shackle is in locked position and guide movement of said instrument in a direction nonproductive of release of said toe notch.
 7. An anti-tamper padlock construction as in claim 6 wherein said side of the cut-out has a portion at a location greater in radial distance from the axis of rotation of said locking plate and outside said access aperture than is the bottom of the cut-out, said side having a potential direction of movement against said unauthorized instrument when said locking plate is subjected to unauthorized rotation. 